from typing import Optional

import pandas as pd
from pydruid.db import connect

from mindsdb_sql_parser import parse_sql
from mindsdb.utilities.render.sqlalchemy_render import SqlalchemyRender
from mindsdb.integrations.libs.base import DatabaseHandler
from pydruid.db.sqlalchemy import DruidDialect

from mindsdb_sql_parser import ASTNode

from mindsdb.utilities import log
from mindsdb.integrations.libs.response import (
    HandlerStatusResponse as StatusResponse,
    HandlerResponse as Response,
    RESPONSE_TYPE,
)

logger = log.getLogger(__name__)


class DruidHandler(DatabaseHandler):
    """
    This handler handles connection and execution of the Apache Druid statements.
    """

    name = "druid"

    def __init__(self, name: str, connection_data: Optional[dict], **kwargs):
        """
        Initialize the handler.
        Args:
            name (str): name of particular handler instance
            connection_data (dict): parameters for connecting to the database
            **kwargs: arbitrary keyword arguments.
        """
        super().__init__(name)
        self.parser = parse_sql
        self.dialect = "druid"

        optional_parameters = ["user", "password"]
        for parameter in optional_parameters:
            if parameter not in connection_data:
                connection_data[parameter] = None

        if "path" not in connection_data:
            connection_data["path"] = "/druid/v2/sql/"

        if "scheme" not in connection_data:
            connection_data["scheme"] = "http"

        self.connection_data = connection_data
        self.kwargs = kwargs

        self.connection = None
        self.is_connected = False

    def __del__(self):
        if self.is_connected is True:
            self.disconnect()

    def connect(self) -> StatusResponse:
        """
        Set up the connection required by the handler.
        Returns:
            HandlerStatusResponse
        """

        if self.is_connected is True:
            return self.connection

        self.connection = connect(
            host=self.connection_data["host"],
            port=self.connection_data["port"],
            path=self.connection_data["path"],
            scheme=self.connection_data["scheme"],
            user=self.connection_data["user"],
            password=self.connection_data["password"],
        )
        self.is_connected = True

        return self.connection

    def disconnect(self):
        """
        Close any existing connections.
        """

        if self.is_connected is False:
            return

        self.connection.close()
        self.is_connected = False
        return self.is_connected

    def check_connection(self) -> StatusResponse:
        """
        Check connection to the handler.
        Returns:
            HandlerStatusResponse
        """

        response = StatusResponse(False)
        need_to_close = self.is_connected is False

        try:
            conn = self.connect()
            conn.cursor().execute("select 1")  # raise exception if provided wrong credentials

            response.success = True
        except Exception as e:
            logger.error(f"Error connecting to Druid, {e}!")
            response.error_message = str(e)
        finally:
            if response.success is True and need_to_close:
                self.disconnect()
            if response.success is False and self.is_connected is True:
                self.is_connected = False

        return response

    def native_query(self, query: str) -> StatusResponse:
        """
        Receive raw query and act upon it somehow.
        Args:
            query (str): query in native format
        Returns:
            HandlerResponse
        """

        need_to_close = self.is_connected is False

        connection = self.connect()
        cursor = connection.cursor()

        try:
            cursor.execute(query)
            result = cursor.fetchall()
            if result:
                response = Response(
                    RESPONSE_TYPE.TABLE, data_frame=pd.DataFrame(result, columns=[x[0] for x in cursor.description])
                )
            else:
                connection.commit()
                response = Response(RESPONSE_TYPE.OK)
        except Exception as e:
            logger.error(f"Error running query: {query} on Pinot!")
            response = Response(RESPONSE_TYPE.ERROR, error_message=str(e))

        cursor.close()
        if need_to_close is True:
            self.disconnect()

        return response

    def query(self, query: ASTNode) -> StatusResponse:
        """
        Receive query as AST (abstract syntax tree) and act upon it somehow.
        Args:
            query (ASTNode): sql query represented as AST. May be any kind
                of query: SELECT, INTSERT, DELETE, etc
        Returns:
            HandlerResponse
        """
        renderer = SqlalchemyRender(DruidDialect)
        query_str = renderer.get_string(query, with_failback=True)
        return self.native_query(query_str)

    def get_tables(self) -> StatusResponse:
        """
        Return list of entities that will be accessible as tables.
        Returns:
            HandlerResponse
        """

        query = """
            SELECT 
                TABLE_SCHEMA AS table_schema,
                TABLE_NAME AS table_name,
                TABLE_TYPE AS table_type
            FROM INFORMATION_SCHEMA.TABLES
            WHERE TABLE_SCHEMA not in ('INFORMATION_SCHEMA', 'sys')
        """
        result = self.native_query(query)

        return result

    def get_columns(self, table_name: str, schema_name: Optional[str] = None) -> StatusResponse:
        """
        Returns a list of entity columns.
        Args:
            table_name (str): name of one of tables returned by self.get_tables()
        Returns:
            HandlerResponse
        """
        if schema_name is None:
            schema_name = "druid"
        query = f"""
            SELECT
                COLUMN_NAME FIELD,
                DATA_TYPE TYPE
            FROM INFORMATION_SCHEMA.COLUMNS
            WHERE "TABLE_SCHEMA" = '{schema_name}' AND "TABLE_NAME" = '{table_name}'
        """
        result = self.native_query(query)

        return result
